/*
** $Id: lmathlib.c,v 1.119 2016/12/22 13:08:50 roberto Exp $
** Standard mathematical library
** See Copyright Notice in lua.h
*/

#define lmathlib_c
#define LUA_LIB

#include "lprefix.h"


#include <stdlib.h>
#include <math.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


#undef PI
#define PI  (l_mathop(3.141592653589793238462643383279502884))


#if !defined(l_rand)        /* { */
    #if defined(LUA_USE_POSIX)
        #define l_rand()    random()
        #define l_srand(x)  srandom(x)
        #define L_RANDMAX   2147483647  /* (2^31 - 1), following POSIX */
    #else
        #define l_rand()    rand()
        #define l_srand(x)  srand(x)
        #define L_RANDMAX   RAND_MAX
    #endif
#endif              /* } */


static int math_abs(lua_State *L)
{
    if (lua_isinteger(L, 1))
    {
        lua_Integer n = lua_tointeger(L, 1);

        if (n < 0) n = (lua_Integer)(0u - (lua_Unsigned)n);

        lua_pushinteger(L, n);
    }
    else
        lua_pushnumber(L, l_mathop(fabs)(luaL_checknumber(L, 1)));

    return 1;
}

static int math_sin(lua_State *L)
{
    lua_pushnumber(L, l_mathop(sin)(luaL_checknumber(L, 1)));
    return 1;
}

static int math_cos(lua_State *L)
{
    lua_pushnumber(L, l_mathop(cos)(luaL_checknumber(L, 1)));
    return 1;
}

static int math_tan(lua_State *L)
{
    lua_pushnumber(L, l_mathop(tan)(luaL_checknumber(L, 1)));
    return 1;
}

static int math_asin(lua_State *L)
{
    lua_pushnumber(L, l_mathop(asin)(luaL_checknumber(L, 1)));
    return 1;
}

static int math_acos(lua_State *L)
{
    lua_pushnumber(L, l_mathop(acos)(luaL_checknumber(L, 1)));
    return 1;
}

static int math_atan(lua_State *L)
{
    lua_Number y = luaL_checknumber(L, 1);
    lua_Number x = luaL_optnumber(L, 2, 1);
    lua_pushnumber(L, l_mathop(atan2)(y, x));
    return 1;
}


static int math_toint(lua_State *L)
{
    int valid;
    lua_Integer n = lua_tointegerx(L, 1, &valid);

    if (valid)
        lua_pushinteger(L, n);
    else
    {
        luaL_checkany(L, 1);
        lua_pushnil(L);  /* value is not convertible to integer */
    }

    return 1;
}


static void pushnumint(lua_State *L, lua_Number d)
{
    lua_Integer n;

    if (lua_numbertointeger(d, &n))  /* does 'd' fit in an integer? */
        lua_pushinteger(L, n);  /* result is integer */
    else
        lua_pushnumber(L, d);  /* result is float */
}


static int math_floor(lua_State *L)
{
    if (lua_isinteger(L, 1))
        lua_settop(L, 1);  /* integer is its own floor */
    else
    {
        lua_Number d = l_mathop(floor)(luaL_checknumber(L, 1));
        pushnumint(L, d);
    }

    return 1;
}


static int math_ceil(lua_State *L)
{
    if (lua_isinteger(L, 1))
        lua_settop(L, 1);  /* integer is its own ceil */
    else
    {
        lua_Number d = l_mathop(ceil)(luaL_checknumber(L, 1));
        pushnumint(L, d);
    }

    return 1;
}


static int math_fmod(lua_State *L)
{
    if (lua_isinteger(L, 1) && lua_isinteger(L, 2))
    {
        lua_Integer d = lua_tointeger(L, 2);

        if ((lua_Unsigned)d + 1u <= 1u)    /* special cases: -1 or 0 */
        {
            luaL_argcheck(L, d != 0, 2, "zero");
            lua_pushinteger(L, 0);  /* avoid overflow with 0x80000... / -1 */
        }
        else
            lua_pushinteger(L, lua_tointeger(L, 1) % d);
    }
    else
        lua_pushnumber(L, l_mathop(fmod)(luaL_checknumber(L, 1),
                                         luaL_checknumber(L, 2)));

    return 1;
}


/*
** next function does not use 'modf', avoiding problems with 'double*'
** (which is not compatible with 'float*') when lua_Number is not
** 'double'.
*/
static int math_modf(lua_State *L)
{
    if (lua_isinteger(L, 1))
    {
        lua_settop(L, 1);  /* number is its own integer part */
        lua_pushnumber(L, 0);  /* no fractional part */
    }
    else
    {
        lua_Number n = luaL_checknumber(L, 1);
        /* integer part (rounds toward zero) */
        lua_Number ip = (n < 0) ? l_mathop(ceil)(n) : l_mathop(floor)(n);
        pushnumint(L, ip);
        /* fractional part (test needed for inf/-inf) */
        lua_pushnumber(L, (n == ip) ? l_mathop(0.0) : (n - ip));
    }

    return 2;
}


static int math_sqrt(lua_State *L)
{
    lua_pushnumber(L, l_mathop(sqrt)(luaL_checknumber(L, 1)));
    return 1;
}


static int math_ult(lua_State *L)
{
    lua_Integer a = luaL_checkinteger(L, 1);
    lua_Integer b = luaL_checkinteger(L, 2);
    lua_pushboolean(L, (lua_Unsigned)a < (lua_Unsigned)b);
    return 1;
}

static int math_log(lua_State *L)
{
    lua_Number x = luaL_checknumber(L, 1);
    lua_Number res;

    if (lua_isnoneornil(L, 2))
        res = l_mathop(log)(x);
    else
    {
        lua_Number base = luaL_checknumber(L, 2);
#if !defined(LUA_USE_C89)

        if (base == l_mathop(2.0))
            res = l_mathop(log2)(x);
        else
#endif
            if (base == l_mathop(10.0))
                res = l_mathop(log10)(x);
            else
                res = l_mathop(log)(x) / l_mathop(log)(base);
    }

    lua_pushnumber(L, res);
    return 1;
}

static int math_exp(lua_State *L)
{
    lua_pushnumber(L, l_mathop(exp)(luaL_checknumber(L, 1)));
    return 1;
}

static int math_deg(lua_State *L)
{
    lua_pushnumber(L, luaL_checknumber(L, 1) * (l_mathop(180.0) / PI));
    return 1;
}

static int math_rad(lua_State *L)
{
    lua_pushnumber(L, luaL_checknumber(L, 1) * (PI / l_mathop(180.0)));
    return 1;
}


static int math_min(lua_State *L)
{
    int n = lua_gettop(L);  /* number of arguments */
    int imin = 1;  /* index of current minimum value */
    int i;
    luaL_argcheck(L, n >= 1, 1, "value expected");

    for (i = 2; i <= n; i++)
    {
        if (lua_compare(L, i, imin, LUA_OPLT))
            imin = i;
    }

    lua_pushvalue(L, imin);
    return 1;
}


static int math_max(lua_State *L)
{
    int n = lua_gettop(L);  /* number of arguments */
    int imax = 1;  /* index of current maximum value */
    int i;
    luaL_argcheck(L, n >= 1, 1, "value expected");

    for (i = 2; i <= n; i++)
    {
        if (lua_compare(L, imax, i, LUA_OPLT))
            imax = i;
    }

    lua_pushvalue(L, imax);
    return 1;
}

/*
** This function uses 'double' (instead of 'lua_Number') to ensure that
** all bits from 'l_rand' can be represented, and that 'RANDMAX + 1.0'
** will keep full precision (ensuring that 'r' is always less than 1.0.)
*/
static int math_random(lua_State *L)
{
    lua_Integer low, up;
    double r = (double)l_rand() * (1.0 / ((double)L_RANDMAX + 1.0));

    switch (lua_gettop(L))    /* check number of arguments */
    {
        case 0:    /* no arguments */
        {
            lua_pushnumber(L, (lua_Number)r);  /* Number between 0 and 1 */
            return 1;
        }

        case 1:    /* only upper limit */
        {
            low = 1;
            up = luaL_checkinteger(L, 1);
            break;
        }

        case 2:    /* lower and upper limits */
        {
            low = luaL_checkinteger(L, 1);
            up = luaL_checkinteger(L, 2);
            break;
        }

        default:
            return luaL_error(L, "wrong number of arguments");
    }

    /* random integer in the interval [low, up] */
    luaL_argcheck(L, low <= up, 1, "interval is empty");
    luaL_argcheck(L, low >= 0 || up <= LUA_MAXINTEGER + low, 1,
                  "interval too large");
    r *= (double)(up - low) + 1.0;
    lua_pushinteger(L, (lua_Integer)r + low);
    return 1;
}


static int math_randomseed(lua_State *L)
{
    l_srand((unsigned int)(lua_Integer)luaL_checknumber(L, 1));
    (void)l_rand(); /* discard first value to avoid undesirable correlations */
    return 0;
}


static int math_type(lua_State *L)
{
    if (lua_type(L, 1) == LUA_TNUMBER)
    {
        if (lua_isinteger(L, 1))
            lua_pushliteral(L, "integer");
        else
            lua_pushliteral(L, "float");
    }
    else
    {
        luaL_checkany(L, 1);
        lua_pushnil(L);
    }

    return 1;
}


/*
** {==================================================================
** Deprecated functions (for compatibility only)
** ===================================================================
*/
#if defined(LUA_COMPAT_MATHLIB)

static int math_cosh(lua_State *L)
{
    lua_pushnumber(L, l_mathop(cosh)(luaL_checknumber(L, 1)));
    return 1;
}

static int math_sinh(lua_State *L)
{
    lua_pushnumber(L, l_mathop(sinh)(luaL_checknumber(L, 1)));
    return 1;
}

static int math_tanh(lua_State *L)
{
    lua_pushnumber(L, l_mathop(tanh)(luaL_checknumber(L, 1)));
    return 1;
}

static int math_pow(lua_State *L)
{
    lua_Number x = luaL_checknumber(L, 1);
    lua_Number y = luaL_checknumber(L, 2);
    lua_pushnumber(L, l_mathop(pow)(x, y));
    return 1;
}

static int math_frexp(lua_State *L)
{
    int e;
    lua_pushnumber(L, l_mathop(frexp)(luaL_checknumber(L, 1), &e));
    lua_pushinteger(L, e);
    return 2;
}

static int math_ldexp(lua_State *L)
{
    lua_Number x = luaL_checknumber(L, 1);
    int ep = (int)luaL_checkinteger(L, 2);
    lua_pushnumber(L, l_mathop(ldexp)(x, ep));
    return 1;
}

static int math_log10(lua_State *L)
{
    lua_pushnumber(L, l_mathop(log10)(luaL_checknumber(L, 1)));
    return 1;
}

#endif
/* }================================================================== */



static const luaL_Reg mathlib[] =
{
    {"abs",   math_abs},
    {"acos",  math_acos},
    {"asin",  math_asin},
    {"atan",  math_atan},
    {"ceil",  math_ceil},
    {"cos",   math_cos},
    {"deg",   math_deg},
    {"exp",   math_exp},
    {"tointeger", math_toint},
    {"floor", math_floor},
    {"fmod",   math_fmod},
    {"ult",   math_ult},
    {"log",   math_log},
    {"max",   math_max},
    {"min",   math_min},
    {"modf",   math_modf},
    {"rad",   math_rad},
    {"random",     math_random},
    {"randomseed", math_randomseed},
    {"sin",   math_sin},
    {"sqrt",  math_sqrt},
    {"tan",   math_tan},
    {"type", math_type},
#if defined(LUA_COMPAT_MATHLIB)
    {"atan2", math_atan},
    {"cosh",   math_cosh},
    {"sinh",   math_sinh},
    {"tanh",   math_tanh},
    {"pow",   math_pow},
    {"frexp", math_frexp},
    {"ldexp", math_ldexp},
    {"log10", math_log10},
#endif
    /* placeholders */
    {"pi", NULL},
    {"huge", NULL},
    {"maxinteger", NULL},
    {"mininteger", NULL},
    {NULL, NULL}
};


/*
** Open math library
*/
LUAMOD_API int luaopen_math(lua_State *L)
{
    luaL_newlib(L, mathlib);
    lua_pushnumber(L, PI);
    lua_setfield(L, -2, "pi");
    lua_pushnumber(L, (lua_Number)HUGE_VAL);
    lua_setfield(L, -2, "huge");
    lua_pushinteger(L, LUA_MAXINTEGER);
    lua_setfield(L, -2, "maxinteger");
    lua_pushinteger(L, LUA_MININTEGER);
    lua_setfield(L, -2, "mininteger");
    return 1;
}

